1. Field of the Invention
The present invention relates to an eye direction detecting method for detecting the human eye direction.
This application is related to the commonly assigned application Ser. No. 07/576,191, (U.S. Pat. No. 5,327,191) the disclosure of which are expressly incorporated in its entirety by reference herein.
2. Description of Related Art
Application Ser. No. 07/576,191 (U.S. Pat. No. 5,327,191) discloses an eye direction detecting apparatus which has a line sensor including a photoconductive bit element array on which collimated eye direction detecting light flux which is incident upon an eye ball and is reflected thereby impinges to detect the eye direction in accordance with the output signal of the line sensor. The light flux reflected by the eye ball includes a peak signal (e.g., first Purkinje image) which varies the peak position thereof in accordance with the eye direction and also includes a signal (first signal level) corresponding to the light flux reflected by the iris and a signal (second signal level) corresponding to light flux reflected by an eyeground (also referred to as a retina portion of the eye). The point of change between the first signal level and the second signal level gives information on a position of the inner edge of the iris, and accordingly, the edge of the pupil. Accordingly, the eye direction can be detected in accordance with information of the position of the pupil edge and information of the position of the peak signal.
In this eye direction detecting method, the position of the peak signal can be relatively easily and precisely detected, but it is very difficult to precisely detect the point of change (e.g., boundary) between the first signal level and the second signal level due to noise contained therein. The inaccurate detection of the edge of the pupil results in an imprecise detection of the eye direction.